1. Field of the Invention
The present invention is directed to a moisture barrier and bacteria barrier, which is connected to a measuring tube that is arranged in the flow paths of a respirator, for protecting medical components in communication with the measuring tube.
2. Description of the Prior Art
In order to be able to monitor and control a respirator, a number of parameters, preferably at the expiration side, are measured using medical components. The medical components are preferably arranged in a fluid-tight manner in a unit, which is connected at the measuring tube. It is known to connect a moisture barrier and bacteria barrier to the entrance of the measuring tube in the form of a filter, which is arranged in a mouthpiece made of plastic, in order to protect the medical components against xe2x80x9ccontaminationsxe2x80x9d in the breathing air, such as drugs and body fluids. Thus, an autoclaving of the medical components, most of which are sensitive and would become uncalibrated or damaged due to autoclaving can be avoided. The mouthpiece made of plastic and the filter are for the most part formed of a disposable material that is thrown away after each utilization and these are replaced with a new mouthpiece with filter when a new patient is connected to the respirator. This disposable product entails relatively high costs for the hospital and also has environmental concerns associated therewith. Moreover, the filter represents a specific flow resistance in the expiration line. When the filter is used for a longer period, it can become occluded; thereby producing a flow resistance that is excessively high. This, in turn, can lead to an increased pressure in the lungs and a greater risk for lung or respiratory injury.
European Application 0 841 083 proposes a solution for this problem in a method and an arrangement for the functional control of filters in order to optimize the period of use without the risk of the patient-related problems.
U.S. Pat. No. 5,419,326 describes an ultrasound fluxmeter in which the transmitter and the receiver are arranged at a distance from each other along a measuring path, which extends obliquely relative to the axis of a tubular measuring chamber. A sterile insertion tube is introduced into the measuring chamber for each new patient. The sterile tube is provided with measuring windows that are adapted to lie above the openings in the measuring chamber. Membranes are arranged in the measuring windows; these membranes being permeable to ultrasound signals but impermeable to moisture and bacteria, so that the ultrasound signals can pass along the measuring path through the sterile insertion tube. Autoclaving the fluxmeter after each use thus is avoided, which is an advantage since the ultrasound transmitting unit and the reception unit, in particular, are sensitive parts in the fluxmeter. The membranes are arranged at a distance from the ultrasound transmitting heads and reception heads. The signals must initially pass through the membrane and then a relatively large air gap, so that the ultrasound signals can reach the transmitting unit, or the reception unit. This passage from the membrane to a relatively large air gap can lead to a high acoustic impedance, i.e., a high sound wave reflection. This can lead to relatively high acoustic losses, so that a low sound signal, which cannot be detected, reaches the reception head. One response this problem is to dispose the membrane closely at the ultrasound transmitting heads and reception heads. Given such a solution, which is described in the Swedish patent application 9801007 (corresponding to co-pending U.S. application Ser. No. 09/274,862, filed Mar. 23, 1999 entitled xe2x80x9cDevice for Measuring a Gas Flow,xe2x80x9d Wallen et al., assigned to the same Assignee as the present application), the membranes are not mounted at a sterile insertion tube but are directly fastened at the transmitting heads and reception heads.
There are other medical components which also require the membrane or the filter to be disposed close to the component in order to receive the best possible measuring result. Given the arrangement described in U.S. Pat. No. 5,419,326, it can be difficult, due to the wall thickness of the measuring chamber, to closely mount the barrier relative to a medical component, since the carrier for the barrier must be pushed into and placed in the measuring chamber. Although two barriers are attached at the sterile tube, these two barriers are merely provided for one single medical component.
An object of the present invention is to provide a relatively simple and inexpensive moisture barrier and bacteria barrier, which can be exchanged and does not cause a flow resistance in the flow paths of a respirator, for protecting medical components.
This object is inventively achieved in a carrier on which at least two barriers (which can be moisture or bacteria barriers) are mounted such that one barrier is arranged exactly in front of each medical component, when the carrier is introduced into the respirator. A filter at the entrance of the measuring tube, with the aforementioned disadvantages associated therewith, is avoided. By means of the invention, each medical component that is connected to the measuring tube can have an individually adapted barrier. If required, the barriers can be closely applied at the component or can be mounted so as to be spaced from the component. Because the barriers are mounted at a common carrier, they can be exchanged in a fast and simple manner, if required. Since a carrier of this type is relatively simple in its construction, the manufacturing costs can be kept low.
In a respirator with a measuring tube in which firmly mounted components are arranged, the inventive carrier can be attached between the measuring tube and the unit in which the components are mounted. By the placement of the carrier, the barriers can, if required, be closely disposed relative to a component, unlike the aforementioned arrangement described in U.S. Pat. No. 5,419,326.
Since the medical components in the unit are usually arranged in succession, the carrier preferably has an elongated form. The cross-section profile of the carrier is preferably adapted to the outside profile of the measuring tube. The carrier is preferably manufactured from a plastic material.
In an embodiment of the invention the peripheral surface of the carrier is provided with a seal that can be placed adjacent the measuring tube given an introduced carrier. It is thus assured that gas does not seep out of the measuring tube.
According to the invention, the barriers are filters and/or membranes.
As already mentioned, the carrier is inventively exchangeable. Thus, a new carrier can be introduced before each new patient.